Information recording medium for recording a scrambled part of content information, and method and apparatus for reproducing information recorded therein

ABSTRACT

An information recording medium, such as an optical disk or the like, is provided for recording at least copyrighted content information and cipher key information. A part of the content information is scrambled and recorded in the information recording medium, and the scrambled and recorded part of the content information is obtained through scrambling using scramble key information, which is obtained by converting the cipher key information by the use of a non-scrambled part of the content information. The information recording medium has a recording area divided into a plurality of sectors. A plurality of data which the content information is divided into is recorded in the sectors. The non-scrambled part of the content information includes copy control information and a part of the content information that changes sector by sector.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information recording medium forrecording video information, audio information or the like, a method forreproducing information recorded in the information recording medium,and an apparatus for reproducing information recorded in the informationrecording medium. In particular, the present invention relates to aninformation recording medium in which copyrighted content information isrecorded, a method for reproducing copyrighted content informationrecorded in the information recording medium, and an apparatus forreproducing copyrighted content information recorded in the informationrecording medium.

2. Description of the Related Art

Recently, recording mediums, each for recording an analog signal, suchas a compact cassette tape, an analog record and the like, have beenreplaced as the mainstream of recording mediums for audio information bya recording medium for recording a digital signal, such as a CD (CompactDisc), a MD (Mini Disc) and the like. Moreover, the digital recordingmediums, such as a video CD for recording a video signal compressed by acompression method called MPEG1 on a CD, and a DVD (Digital Video Disc)for recording a video signal compressed by a high-quality compressionmethod called MPEG2 on an optical disk having a large capacity of 4.7GB, have been developed as recording mediums for recording a videosignal. These digital recording mediums have been commercialized asrecording mediums for recording video information and audio information.

FIG. 7 is a block diagram showing an internal configuration of anoptical disk reproducing apparatus 400 of a first prior art. The opticaldisk reproducing apparatus 400 executes error correction and expansionprocesses on information data read out from an optical disk 201, therebydecoding and outputting desired video and audio signals.

Referring to FIG. 7, the optical disk reproducing apparatus 400 isequipped with the optical disk 201. The optical disk reproducingapparatus 400 is constituted by a spindle motor 202, an optical head203, a head amplifier 204, an analog processor 205, an optical diskcontroller 206, an error correction memory 207, an audio and videodecoder 209 (hereinafter referred to as an AV decoder), an audio andvideo signal processing memory 210 (hereinafter referred to as an AVsignal processing memory), a servo controller 211, a CPU 212, and a CPUbus 213.

The spindle motor 202 rotates the optical disk 201 in accordance with acontrol signal from the servo controller 211. The optical head 203comprises an optical pickup. The optical head 203 irradiates the opticaldisk 201 with laser light generated by driving a laser diode. Theoptical head 203 detects the reflected light from the optical disk 201,and then, executes photoelectric conversion on the reflected light.Then, the optical head 203 outputs a reproduced signal subjected tophotoelectric conversion to the analog processor 205 through the headamplifier 204. The analog processor 205 has facilities for AGC,equalizing, data slice, and PLL. The analog processor 205 appliespredetermined analog signal processing to the input reproduced signal,and then outputs the processed reproduced signal to the optical diskcontroller 206. Subsequently, the optical disk controller 206 convertsthe input reproduced signal into reproduced digital data through A/Dconversion, and then demodulates the reproduced data. The optical diskcontroller 206 applies error correction and the like to the demodulatedreproduced data by using the error correction memory 207 as a buffermemory.

Then, the optical disk controller 206 outputs the processed reproduceddata to the AV decoder 209. Furthermore, the AV decoder 209 appliesdecoding including expansion to video data and audio data, which arecompressed into the above-mentioned input reproduced data, by using theAV signal processing memory 210 that is an expansion buffer memory foruse in expansion of video data and audio data, in accordance with theinput reproduced data. Then, the AV decoder 209 outputs the processedvideo and audio signals.

The servo controller 211 controls the spindle motor 202, the opticalhead 203, the optical disk controller 206 and so on in accordance withthe signals from the analog processor 205, the optical disk controller206 and the CPU 212, to perform servo control of focusing, tracking orthe like of the optical head 203 for readout of data from the opticaldisk 201, or the like. The servo controller 211, the analog processor205, the optical disk controller 206 and the AV decoder 209 areconnected to the CPU 212 through the CPU bus 213. The CPU 212 controlsthe analog processor 205, the optical disk controller 206, the AVdecoder 209 and the servo controller 211 through the CPU bus 213, tocontrol operation of the overall optical disk reproducing apparatus 400.

An operation of the optical disk reproducing apparatus of the firstprior art will be briefly described with reference to FIG. 7. The CPU212 controls the optical head 203 in accordance with a predeterminedsequence so as to read out data from the optical disk 201 by using theoptical head 203, then output the reproduced data to the optical diskcontroller 206 through the head amplifier 204 and the analog processor205, and then store the reproduced data subjected to error correction inthe error correction memory 207. At that time, the CPU 212 reads outcontrol information and data identification information in thereproduced data stored in the error correction memory 207, and thuscontrols the servo controller 211 and the AV decoder 209, therebyreproducing video data and audio data.

On the other hand, the capacity of an application program for a personalcomputer has also increased in accordance with an improvement inperformance of the personal computer and an increase in the capacity ofa hard disk. A DVD is used, by making use of its large capacity, notonly as a recording medium for recording video data and audio data, butalso as a medium for distributing application software for the personalcomputer, or the like. Thus, a DVD drive unit is rapidly spreading as aperipheral unit of the personal computer. Furthermore, an AV decodercard having an MPEG expansion facility for the personal computer, aprogram for executing the MPEG expansion facility through softwareprocessing by a main processor of the personal computer and the likehave been commercialized.

However, the DVD drive unit and the AV decoder card are connectedthrough a communication line of a general computer bus in a system inwhich the personal computer reproduces video data and audio data fromthe DVD by using the DVD drive unit and the AV decoder card. Thus, acts,such as piracy of data transmitted through the communication line anddistribution of tampered data, take place. Consequently, there is such aproblem in that it is very difficult to protect the copyright thereof.

In order to solve the above-mentioned problems, encryption and recordingof copyrighted data have been proposed in Japanese patent laid-openpublication No. 7-249264 (hereinafter referred to as a second priorart), for example. Proposed is a method in which a cipher key isrecorded in a main data area of a different sector from an encrypteddata sector in a CD-ROM of the second prior art. In the second priorart, data encrypted at the time of recording and a cipher key of thedata are recorded in the CD-ROM. At the time of reproducing, a personalcomputer issues a command to read a cipher key to a reproducingapparatus, then encrypted data is read out, and the encrypted data isdecrypted by using the cipher key previously read out, and this leads tothe data being reproduced.

However, in the second prior art, the cipher key is recorded in the maindata area of the sector from which the cipher key can be read out by ageneral read command. Thus, the cipher key can be easily read out by ageneral personal computer. Therefore, a user can read out the cipher keyand encrypted data. Thus, the second prior art has a problem in that itinvolves a high risk of decryption. The second prior art has anotherproblem that a pirated copy can be made by copying the cipher key andthe encrypted data in a hard disk memory, for example.

Moreover, all the main data areas of the sector are encrypted andrecorded. Thus, when a CPU of, for example, a DVD player attempts toread out content control information, which is included in main data ofthe sector and includes content identification information, content copycontrol information and so on, from an optical disk in order to controlthe DVD player, the CPU can obtain correct information only afterdecrypting data once encrypted.

The above-mentioned problem causes the following problem. When the areacontaining the content control information is recorded in a form ofplain text, unauthorized reproducing takes place in the case where thecopy control information is tampered with.

SUMMARY OF THE INVENTION

In order to solve the foregoing problems, it is an object of the presentinvention to provide an information recording medium having a datastructure for preventing easy readout of key information for use indescrambling.

In order to solve the foregoing problems, it is another object of thepresent invention to provide an information recording medium in which aCPU for controlling an information reproducing apparatus, such as a DVDplayer, can easily read out copy control information or the like fromthe information recording medium and thus easily control the informationreproducing apparatus, and reproducing of data can be prevented when thecopy control information or the like recorded in the informationrecording medium is tampered with.

In order to solve the foregoing problems, it is a further object of thepresent invention to provide a method and an apparatus for reproducinginformation stored in an information recording medium, in which a CPUfor controlling an information reproducing apparatus, such as a DVDplayer, can easily read out copy control information or the like from aninformation recording medium and thus easily control the informationreproducing apparatus, and reproducing of data can be prevented when thecopy control information or the like recorded in the informationrecording medium is tampered with.

In order to achieve the aforementioned objective, according to oneaspect of the present invention, there is provided an informationrecording medium for recording at least copyrighted content informationand cipher key information,

wherein a part of the content information is scrambled and recorded inthe information recording medium, and

wherein the scrambled and recorded part of the content information isobtained through scrambling using scramble key information, which isobtained by converting the cipher key information by the use of anon-scrambled part of the content information.

In the above-mentioned information recording medium, the non-scrambledpart of the content information for generating the scramble keyinformation preferably includes at least copy control information.

In the above-mentioned information recording medium, the informationrecording medium preferably comprises a recording area divided into aplurality of sectors,

wherein a plurality of data which the content information is dividedinto are recorded in the sectors, respectively, and

wherein the non-scrambled part of the content information for generatingthe scramble key information includes the copy control information, anda part of the content information that changes sector by sector.

According to another aspect of the present invention, there is provideda method for reproducing information recorded in an informationrecording medium for recording at least cipher key information andcontent information, a part of the content information being scrambledand recorded in the information recording medium, the method includingthe steps of:

decoding the cipher key information recorded in the informationrecording medium into decoded key information by using predetermined keyinformation;

converting the decoded key information into converted decoded keyinformation by using non-scrambled content information of the contentinformation; and

descrambling the scrambled and recorded content information by using theconverted decoded key information.

According to a further aspect of the present invention, there isprovided an apparatus for reproducing information recorded in aninformation recording medium for recording at least cipher keyinformation and content information, a part of the content informationbeing scrambled and recorded, the apparatus comprising:

cipher key information decoding means for decoding the cipher keyinformation recorded in the information recording medium into decodedkey information by using predetermined key information;

key information converting means for converting the decoded keyinformation outputted from the cipher key information decoding means,into converted decoded key information by using non-scrambled contentinformation of the content information; and

descrambling means for descrambling the scrambled and recorded contentinformation by using the converted key information outputted from thekey information converting means.

According to a still further aspect of the present invention, there isprovided an information recording medium having at least a datarecording area for recording copyrighted content information,

wherein at least cipher key information and the content information arerecorded in the data recording area,

wherein a part of the content information recorded in the data recordingarea is scrambled and recorded, and

wherein the scrambled and recorded part of the content information isobtained through scrambling using scramble key information, which isobtained by converting the cipher key information by the use of anon-scrambled part of the content information.

According to a still further aspect of the present invention, there isprovided an information recording medium having at least a datarecording area and a lead-in area, copyrighted content information beingrecorded in the information recording medium,

wherein at least first cipher key information and the contentinformation are recorded in the data recording area,

wherein second cipher key information is recorded in the lead-in area,wherein a part of the content information recorded in the data recordingarea is scrambled and recorded, and

wherein the scrambled and recorded content information is obtainedthrough scrambling using scramble key information, which is obtained byconverting the second cipher key information by the use of anon-scrambled part of the content information.

In the above-mentioned information recording medium, the non-scrambledpart of the content information for generating the scramble keyinformation preferably includes at least copy control information.

In the above-mentioned information recording medium, the informationrecording medium preferably has a recording area divided into aplurality of sectors, wherein a plurality of data which the contentinformation is divided into are recorded in the sectors, respectively,and

wherein the non-scrambled part of the content information for generatingthe scramble key information includes the copy control information, anda part of the content information that changes sector by sector.

According to a still further aspect of the present invention, there isprovided a method for reproducing information recorded in an informationrecording medium having at least a data recording area and a lead-inarea, at least first cipher key information and content informationbeing recorded in the data recording area, second cipher key informationbeing recorded in the lead-in area, and a part of the contentinformation recorded in the data recording area being scrambled andrecorded, the method including the steps of:

decoding the first cipher key information stored in the data recordingarea into first key information by using predetermined key information;

decoding the second cipher key information stored in the lead-in areainto second key information by using the first key information;converting the second key information into converted second keyinformation by using non-scrambled content information stored in thedata recording area; and

descrambling the scrambled and recorded content information by using theconverted second key information.

According to a still further aspect of the present invention, there isprovided an apparatus for reproducing information recorded in aninformation recording medium having at least a data recording area and alead-in area, at least first cipher key information and contentinformation being recorded in the data recording area, second cipher keyinformation being recorded in the lead-in area, and a part of thecontent information recorded in the data recording area being scrambledand recorded, the apparatus comprising:

first key information decoding means for decoding the first cipher keyinformation stored in the data recording area into first key informationby using predetermined key information;

second key information decoding means for decoding the second cipher keyinformation stored in the lead-in area into second key information byusing the first key information outputted from the first key informationdecoding means;

key converting means for converting the second key information outputtedfrom the second key information decoding means into converted second keyinformation by using non-scrambled content information of the contentinformation; and

descrambling means for descrambling the scrambled and recorded contentinformation by using the converted second key information outputted fromthe key converting means.

In the above-mentioned apparatus, the non-scrambled content informationfor converting the second key information into the converted second keyinformation preferably includes at least copy control information.

According to a further aspect of the present invention, there isprovided an information recording medium having at least a lead-in areaand a data recording area, copyrighted content information beingrecorded in the information recording medium, wherein first cipher keyinformation is recorded in the lead-in area,

wherein at least second cipher key information and the contentinformation are recorded in the data recording area,

wherein a part of the content information recorded in the data recordingarea is scrambled and recorded, and

wherein the scrambled and recorded content information is obtainedthrough scrambling using scramble key information, which is obtained byconverting the second cipher key information by the use of anon-scrambled part of the content information.

In the above-mentioned information recording medium, the data recordingarea is preferably divided into a plurality of sectors, each of which iscomposed of a sector header area for recording information foridentifying the sector, and a main data area for recording the contentinformation,

wherein the second cipher key information is recorded in the sectorheader area,

wherein a part of the content information is scrambled and recorded inthe main data area, and

wherein the scrambled and recorded part of the content information isobtained through scrambling using scramble key information, which isobtained by converting the second cipher key information by the use of anon-scrambled part of the content information for each sector.

In the above-mentioned information recording medium, the non-scrambledpart of the content information for generating the scramble keyinformation preferably includes at least copy control information.

In the above-mentioned information recording medium, the non-scrambledpart of the content information for generating the scramble keyinformation preferably includes at least the copy control information,and a part of the content information that changes sector by sector.

In the above-mentioned information recording medium, the second cipherkey information recorded in the sector header area is preferablyinformation which is obtained by encrypting predetermined second keyinformation by the use of the first cipher key information recorded inthe lead-in area.

According to a still further aspect of the present invention, there isprovided a method for reproducing information recorded in an informationrecording medium having at least a lead-in area and a data recordingarea, first cipher key information being recorded in the lead-in area,at least second cipher key information and content information beingrecorded in the data recording area, and a part of the contentinformation recorded in the data recording area being scrambled andrecorded in the information recording medium, the method including thesteps of:

decoding the first cipher key information stored in the lead-in areainto first key information by using predetermined key information;decoding the second cipher key information stored in the data recordingarea into second key information by using the first key information;

converting the second key information into converted second keyinformation by using non-scrambled content information stored in thedata recording area; and

descrambling the scrambled and recorded content information by using theconverted second key information.

According to a still further aspect of the present invention, there isprovided an apparatus for reproducing information recorded in aninformation recording medium having at least a lead-in area and a datarecording area, first cipher key information being recorded in thelead-in area, at least second cipher key information and contentinformation being recorded in the data recording area, and a part of thecontent information recorded in the data recording area being scrambledand recorded in the information recording medium, the apparatuscomprising:

first key information decoding means for decoding the first cipher keyinformation stored in the lead-in area into first key information byusing predetermined key information;

second key information decoding means for decoding the second cipher keyinformation stored in the data recording area into second keyinformation by using the first key information outputted from the firstkey information decoding means;

key information converting means for converting the second keyinformation outputted from the second key information decoding meansinto converted second key information by using non-scrambled contentinformation stored in the data recording area; and

descrambling means for descrambling the scrambled and recorded contentinformation by using the converted second key information outputted fromthe key information converting means.

In the above-mentioned apparatus, a non-scrambled part of the contentinformation preferably includes at least copy control information.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clear from the following description taken in conjunction withthe preferred embodiments thereof with reference to the accompanyingdrawings throughout which like parts are designated by like referencenumerals, and in which:

FIG. 1 is a hierarchy diagram showing a data structure of an opticaldisk 201 according to a first preferred embodiment of the presentinvention;

FIG. 2 is a plan view of recording areas of the optical disk 201 shownin FIG. 1;

FIG. 3 is a block diagram showing an internal configuration of anoptical disk reproducing apparatus 200 for reproducing informationrecorded in the optical disk 201 shown in FIGS. 1 and 2;

FIG. 4 is a block diagram showing an internal configuration of adescrambling circuit 208 shown in FIG. 3;

FIG. 5 is a hierarchy diagram showing a data structure of the opticaldisk 201 according to a second preferred embodiment of the presentinvention;

FIG. 6 is block diagram showing an internal configuration of adescrambling circuit 208 a for use in the second preferred embodiment;and

FIG. 7 is a block diagram showing an internal configuration of anoptical disk reproducing apparatus 400 of the first prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An optical disk, a method of reproducing information recorded in theoptical disk and an apparatus for reproducing information recorded inthe optical disk according to preferred embodiments of the presentinvention will be described below with reference to the accompanyingdrawings. Herein, optical disks include an optical disk, and amagneto-optical disk such as a CD, a video CD, a CD-ROM, a CD-R, aCD-RW, an MD, a DVD, a DVD-ROM, a DVD-RAM, a DVD-RW or the like.

First Preferred Embodiment

FIG. 1 is a hierarchy diagram showing a data structure of an opticaldisk 201 according to a first preferred embodiment of the presentinvention, and FIG. 2 is a plan view of recording areas of the opticaldisk 201 shown in FIG. 1.

In FIG. 1, reference numeral 100A denotes a data structure of aninformation recording area of the whole optical disk 201, and the datastructure 100A comprises a lead-in area 100 for recording controlinformation, a data recording area 101 for recording content information138 composed of content control information 134 and content data 135,and a lead-out area 102. As shown in FIG. 2, the optical disk 201 has arotation driving hole 201 h in the center thereof, and the lead-in area100, the data recording area 101 and the lead-out area 102 are locatedin order from the inside of the optical disk 201 toward the outsidethereof.

Referring to FIG. 1, the lead-in area 100 contains a control data area110 for recording information required for an optical disk reproducingapparatus 200 shown in FIG. 3 to reproduce information from the opticaldisk 201. The control data area 110 comprises a physical informationsector 111, a sector 150 for storing second cipher key information, andso on, as indicated by reference numeral 100B. Physical informationabout the optical disk 201, such as a disk diameter, a disk structure, arecording density and the like, is recorded in the physical informationsector 111. Second cipher key information, which is obtained byencrypting predetermined second key information, is recorded in thesector 150 for storing second cipher key information.

A scramble information sector 151 for recording first cipher keyinformation and the content information 138 such as a compressed movie,music or the like are scrambled, and then recorded as a scrambled file130 in the data recording area 101. As indicated by reference numeral100A of FIG. 1, the first cipher key information is recorded as ascramble information file 120 in the data recording area 101.Copyrighted content information 138 is scrambled and recorded as thescrambled file 130 in the data recording area 101. Copyright-freecontent information 138 is not scrambled and is recorded as anon-scrambled file 140 in the data recording area 101.

The data recording area 101 is partitioned into a plurality of unitscalled sectors. That is, the data recording area 101 is divided into aplurality of sectors. As indicated by reference numerals 100C, 100D and100E, the files 120, 130 and 140 recorded in the data recording area 101comprise a plurality of scramble information sectors 151, a plurality ofscrambled sectors 152 and a plurality of non-scrambled sectors 153,respectively. Each of the scrambled sectors 152 is composed of a sectorheader area 131 of 12 bytes for recording address information 161 andthe like for identifying the sector, and a main data area 132 of 2048bytes for recording the content information 138, as indicated byreference numeral 100F. Each of the non-scrambled sectors 153 iscomposed of a sector header area 141 of 12 bytes for recording theaddress information 161 and the like for identifying the sector, and amain data area 142 of 2048 bytes for recording the content information138, as indicated by reference numeral 100G. Each scramble informationsector 151 having a data structure indicated by reference numeral 100C.has a sector header area and a main data area, in a manner similar tothat of each scrambled sector 152 and each non-scrambled sector 153.

Furthermore, a scramble flag 162, in addition to the above-mentionedaddress information 161, is recorded in each of the respective sectorheader areas 131 and 141 of the sectors 152 and 153. The scramble flags162 recorded in the sector header areas 131 and 141 are flags forindicating whether or not predetermined areas of the respective maindata areas 132 and 142 of the sectors 152 and 153 are scrambled. Thescramble flag 162 of “1” is recorded in the scrambled sector havingscrambled information, whereas the scramble flag 162 of “0” is recordedin the non-scrambled sector having non-scrambled information.

Furthermore, the second cipher key information stored in the sector 150for storing second cipher key information, which is recorded in thelead-in area 100, is decoded into second key information by using firstkey information, which is obtained by decoding the first cipher keyinformation contained in the scramble information file 120 of the datarecording area 101 by the use of predetermined fixed key information.The second key information obtained through decoding is converted intodescramble key information for use in descrambling of main data, byusing copy control information 136 and reference data 137 stored in thecontent information 138.

In the preferred embodiment, the descramble key information is identicalwith scramble key information for use in encryption by a scramblingcircuit corresponding to a descrambling circuit 208. The reference data137 is a part of the content data 135.

As indicated by reference numeral 100H of FIG. 1, not all of the maindata area 132 of the scrambled sector 152 is scrambled. The main dataarea 132, except for the area containing the content control information134 and a part of the content data, is scrambled. The copy controlinformation 136 contains information such as the limit of the number ofcopies of the content information 138 or the like, and downsamplingcontrol to be performed at the time of reproducing information stored inthe optical disk. The scrambled content data is obtained by scramblingand recording a part of the content information 138 stored in apredetermined area by the use of scramble key information, which is theconverted second key information, into which the second key informationobtained through decoding is converted by using the copy controlinformation 136 contained in the content control information 134 and apart of the compressed content data 135 (e.g., the reference data 137 inthe data structure indicated by reference numeral 100H of FIG. 1).

FIG. 3 is a block diagram showing an internal configuration of theoptical disk reproducing apparatus 200 for reproducing informationrecorded in the optical disk 201 shown in FIGS. 1 and 2. The opticaldisk reproducing apparatus 200 will be described below with reference toFIG. 3.

The optical disk reproducing apparatus 200 of the present preferredembodiment descrambles and expands reproduced data read out from theoptical disk 201, thereby decoding and outputting desired video andaudio signals. In FIG. 3, the components having the same configurationsas those shown in FIG. 7 are indicated by the same reference numerals,and the detailed description thereof is omitted.

Referring to FIG. 3, the optical disk reproducing apparatus 200 isequipped with the optical disk 201. The optical disk reproducingapparatus 200 comprises a spindle motor 202, an optical head 203, a headamplifier 204, an analog processor 205, an optical disk controller 206,an error correction memory 207, the descrambling circuit 208, an AVdecoder 209, an AV signal processing memory 210, a servo controller 211,a CPU 212, and a CPU bus 213. That is, the optical disk reproducingapparatus 200 shown in FIG. 3 is characterized in that the descramblingcircuit 208 for descrambling scrambled and recorded information isinterposed between the optical disk controller 206 and the AV decoder209, as compared with an optical disk reproducing apparatus 400 shown inFIG. 7.

Referring again to FIG. 3, the optical disk controller 206 outputsprocessed reproduced data to the descrambling circuit 208. Thedescrambling circuit 208 descrambles the input processed reproduceddata, and then outputs the descrambled reproduced data to the AV decoder209. The servo controller 211, the analog processor 205, the opticaldisk controller 206, the descrambling circuit 208 and the AV decoder 209are connected to the CPU 212 through the CPU bus 213. The CPU 212controls the analog processor 205, the optical disk controller 206, thedescrambling circuit 208, the AV decoder 209 and the servo controller211 through the CPU bus 213, thereby controlling operation of theoverall optical disk reproducing apparatus 200.

The first cipher key information stored in the scramble information file120 recorded in the data recording area 101, the second cipher keyinformation contained in the sector 150 for storing second cipher keyinformation stored in the lead-in area 100, and the copy controlinformation and the reference data 137 that are a part of the contentinformation 138 are inputted to the descrambling circuit 208. Thedescrambling circuit 208 decodes the input first cipher key informationinto the first key information by using predetermined fixed keyinformation. Then, the descrambling circuit 208 decodes the input secondcipher key information into the second key information by using theabove-mentioned first key information. Subsequently, the descramblingcircuit 208 converts the above-mentioned second key information into theconverted second key information, i.e., the descramble key information,by utilizing a predetermined transform equation such as a higher-orderequation having, for example, two variables by the use of the input partof the content information 138. Furthermore, the descrambling circuit208 descrambles main data in a plurality of scrambled sectors 152 havinga data structure indicated by reference numeral 100D in FIG. 1 by usingthe above-mentioned descramble key information.

FIG. 4 is a block diagram showing an internal configuration of thedescrambling circuit 208 shown in FIG. 3. The configuration andoperation of the descrambling circuit 208 will be described below withreference to FIG. 4.

Referring to FIG. 4, the descrambling circuit 208 comprises a firstsignal selector 301, a fixed key information memory 302, a second signalselector 303, a first key information decoder 304, a second keyinformation decoder 305, a data descrambler 306, a third signal selector307, and a key converter unit 310 including a first key informationconverter 311 and a second key information converter 312. Each of thefirst, second and third signal selectors 301, 303 and 307 comprises amultiplexer or a switch circuit, for example.

Referring again to FIG. 4, the first signal selector 301 selects aninternal circuit to which data inputted from the optical disk controller206 to the descrambling circuit 208 is to be outputted, in accordancewith the setting information of the decoding mode inputted from the CPU212 through the CPU bus 213. Specifically, when the input data is thesecond cipher key information recorded in the lead-in area 100, thefirst signal selector 301 outputs the input second cipher keyinformation to the second key information decoder 305. On the otherhand, when the input data is sector data recorded in the data recordingarea 101, the first signal selector 301 outputs the input sector data tothe second signal selector 303. The fixed key information memory 302stores a predetermined fixed key for use in decoding of the first cipherkey information. The sector data outputted from the first signalselector 301 is inputted to the second signal selector 303. The secondsignal selector 303 selects a circuit to which the sector data is to beoutputted, in accordance with the location of the sector data in thesector, i.e., the count of the number of sector data. As shown in FIG.1, the type of the sector data recorded in the data recording area 101is determined in accordance with the location of the sector data in thesector. Thus, in accordance with the count of the number of sector data,as shown in FIG. 4, the second signal selector 303 performs thefollowing operation of:

(a) outputting the input first cipher key information to the first, keyinformation decoder 304 when the input sector data is the first cipherkey information;

(b) outputting input copy control data to the first key informationconverter 311 of the key converter unit 310 when the input sector datais the copy control data;

(c) outputting the input reference data to the second key informationconverter 312 of the key converter unit 310 when the input sector datais the reference data;

(d) outputting the input scramble flag to the third signal selector 307when the input sector data is the scramble flag; or

(e) outputting the input main data to the data descrambler 306 and thethird signal selector 307 when the input sector data is the main data.

The first key information decoder 304 decodes the first cipher keyinformation contained in the scramble information file 120 of the datarecording area 101 outputted from the second signal selector 303, by adecoding method using a cryptosystem which has been already known tothose skilled in the art, such as the DES cryptosystem, the RSAcryptosystem or the like, by the use of the fixed key information readout from the fixed key information memory 302. Thus, the first keyinformation decoder 304 decodes the first cipher key information intothe first key information, and then, outputs the decoded first keyinformation to the second key information decoder 305. Subsequently, thesecond key information decoder 305 decodes the second cipher keyinformation stored in the sector 150 for storing second cipher keyinformation stored in the lead-in area 100 inputted from the firstsignal selector 301, by a decoding method using a cryptosystem which hasbeen already known to those skilled in the art, such as the DEScryptosystem, the RSA cryptosystem or the like, in a manner similar tothat of the first key information decoder 304 by the use of the firstkey information which is obtained through decoding and outputted fromthe first key information decoder 304. Thus, the second key informationdecoder 305 decodes the second cipher key information into the secondkey information, and outputs the second key information to the first keyinformation converter 311 of the key converter unit 310.

The key converter unit 310 comprises the first and second keyinformation converters 311 and 312. The key converter unit 310 convertsthe second key information outputted from the second key informationdecoder 305 into the converted second key information, i.e., thedescramble key information, by using the copy control information andthe reference data outputted from the second signal selector 303. Then,the key converter unit 310 outputs the descramble key information to thedata descrambler 306. The first key information converter 311 convertsthe second key information outputted from the second key informationdecoder 305 into the second key information subjected to first keyinformation conversion, by utilizing a predetermined first transformequation such as a predetermined higher-order equation, e.g., a methodin which two input data are substituted into a higher-order equationhaving two variables so as to calculate a value of the higher-orderequation, by the use of the copy control information outputted from thesecond signal selector 303. Then, the first key information converter311 outputs the converted second key information to the second keyinformation converter 312. Subsequently, the second key informationconverter 312 converts the second key information, which is subjected tofirst key information conversion and outputted from the first keyinformation converter 311, into the second key information subjected tosecond key information conversion, i.e., the converted second keyinformation, by utilizing a predetermined second transform equation suchas a predetermined higher-order equation, e.g., a method in which twoinput data are substituted into a higher-order equation having twovariables so as to calculate a value of the higher-order equation in amanner similar to that of the first key information converter 311, bythe use of the reference data outputted from the second signal selector303. Then, the second key information converter 312 outputs theconverted second key information to the data descrambler 306.

The data descrambler 306 descrambles the main data outputted from thesecond signal selector 303 by using the descramble key informationoutputted from the second key information converter 312 of the keyconverter unit 310. Thus, the data descrambler 306 generates thedescrambled main data, and outputs the descrambled main data to thethird signal selector 307. Data descrambling is executed in thefollowing manner: a pseudo random pattern signal having a predeterminedlength, such as an M-series signal or the like, is generated by using ashift register having a finite length and an adder in a manner similarto that of a transmitter side, and then the exclusive OR of thegenerated pseudo random pattern signal and the input data is calculated.

Subsequently, the third signal selector 307 selects eithernon-descrambled main data outputted from the second signal selector 303or descrambled main data outputted from the data descrambler 306 inaccordance with the scramble flag outputted from the second signalselector 303 and the count of the number of sector data counted in thethird signal selector 307. Then, the third signal selector 307 outputsthe selected main data to the AV decoder 209. When the scramble flag isequal to “1” and the count does not indicate a storage area fornon-scrambled data 163, i.e., when the main data is scrambled, the thirdsignal selector 307 selects the descrambled main data outputted from thedata descrambler 306, and outputs the descrambled main data to the AVdecoder 209. On the other hand, when the scramble flag is equal to “1”and the count indicates the storage area for the non-scrambled data 163,or when the scramble flag is equal to “0”, i.e., when the main data isnot scrambled, the third signal selector 307 selects the non-descrambledmain data outputted from the second signal selector 303, and outputs thenon-descrambled main data to the AV decoder 209.

An operation of the optical disk reproducing apparatus 200 according tothe preferred embodiment configured as described above will be describedwith reference to FIGS. 3 and 4.

When the optical disk 201 is inserted into the optical disk reproducingapparatus 200 upon power-on, or when the optical disk 201 is newlyinserted into the optical disk reproducing apparatus 200, the CPU 212controls the servo controller 211 so that the optical head 203 may readout from the optical disk 201 information data stored in the sector 150for storing second cipher key information stored in the control dataarea 110 in the lead-in area 100 of FIG. 1. An electric signal of thereadout information data is amplified, demodulated and subjected toerror correction by the head amplifier 204, the analog processor 205 andthe optical disk controller 206, respectively. Then, the CPU 212controls the error correction memory 207 to store data on the processedsecond cipher key information therein.

Subsequently, the CPU 212 controls the servo controller 211 so as toread out the sector storing the scramble information file (first cipherkey information) 120 of FIG. 1 from the optical disk 201. An electricsignal of readout information data is amplified, demodulated andsubjected to error correction by the head amplifier 204, the analogprocessor 205 and the optical disk controller 206, respectively. At thattime, in the descrambling circuit 208, a mode of decoding the firstcipher key information is set in accordance with the decoding modesetting information from the CPU 212. The first cipher key informationinputted from the optical disk controller 206 is transferred to thefirst key information decoder 304 by the first signal selector 301 andthe second signal selector 303. Then, the transferred first cipher keyinformation is decoded by the first key information decoder 304 usingthe fixed key information read out from the fixed key information memory302. Then, the first key information obtained through decoding isoutputted to the second key information decoder 305. In the mode ofdecoding the first cipher key information into the first keyinformation, no data is outputted from the descrambling circuit 208.

Subsequently, the second cipher key information already stored in theerror correction memory 207 is read out and outputted to the second keyinformation decoder 305 through the first signal selector 301 of thedescrambling circuit 208. As described above, the first key informationalready obtained through decoding by the first key information decoder304 is inputted to the second key information decoder 305. The secondkey information decoder 305 decodes the input second cipher keyinformation by using the first key information obtained throughdecoding. Thus, the second key information decoder 305 decodes thesecond cipher key information into the second key information, andoutputs the second key information to the first key informationconverter 311 of the key converter unit 310.

Next, an operation of selecting a file in accordance with operation byan apparatus user or the like, and then reproducing a video signal andan audio signal will be described.

The CPU 212 controls the servo controller 211, the optical head 203, theanalog processor 205 and the optical disk controller 206, therebyreading out desired information data from the optical disk 201 andcausing the error correction memory 207 to store the information datasubjected to error correction. Moreover, the CPU 212 sets a mode ofdescrambling data for the descrambling circuit 208. The CPU 212 sets theinformation required for the AV decoder 209, and then controls the errorcorrection memory 207 to transfer the information data subjected toerror correction to the descrambling circuit 208.

In the descrambling circuit 208, the mode of descrambling data is set asthe decoding mode setting information. Thus, the input sector data istransferred to the second signal selector 303 by the first signalselector 301. The second signal selector 303 counts the number of inputsector data, and outputs the input sector data in accordance with thecount in the following manner.

(a) When the above-mentioned count indicates the data locationcontaining the copy control information, the input sector data isoutputted to the first key information converter 311.

(b) When the above-mentioned count indicates the data locationcontaining the reference data, the input sector data is outputted to thesecond key information converter 312.

(c) When the above-mentioned count indicates the data locationcontaining the main data, the input sector data is outputted to the datadescrambler 306 and the third signal selector 307.

The second key information, which is obtained through decoding andoutputted from the second key information decoder 305, is converted intothe second key information subjected to first key information conversionby the first key information converter 311 by the use of the copycontrol information contained in the main data. Then, the convertedsecond key information is outputted to the second key informationconverter 312. Subsequently, the second key information, which issubjected to first key information conversion and outputted from thefirst key information converter 311, is converted into the convertedsecond key information, i.e., the descramble key information, by thesecond key information converter 312 by the use of the reference datacontained in the main data. Then, the descramble key information isoutputted to the data descrambler 306. Furthermore, the main datainputted to the data descrambler 306 is descrambled by using thedescramble key information outputted from the key converter unit 310.Then, the descrambled main data is outputted to the third signalselector 307.

The third signal selector 307 receives the scramble flag selected by thesecond signal selector 303, counts the number of sector data therein,generates a select signal in accordance with the scramble flag and thecount, and selectively outputs either the main data from the datadescrambler 306 or the main data from the second signal selector 303 inaccordance with the generated select signal. In accordance with thegenerated select signal, when the scramble flag is equal to “1” and thecount of the number of sector data indicates the recording area forrecording the non-scrambled data 163, the non-descrambled main dataoutputted from the second signal selector 303 is outputted from thethird signal selector 307. On the other hand, when the scramble flag isequal to “1” and the count of the number of sector data indicates astorage area for scrambled data 164, the main data outputted from thedata descrambler 306 is outputted from the third signal selector 307. Inaccordance with the generated select signal, when the scramble flag isequal to “0”, the non-descrambled main data outputted from the secondsignal selector 303 is outputted from the third signal selector 307regardless of the count of the number of sector data.

As mentioned above, the main data descrambled in accordance with thescramble flag and the count of the number of sector data is outputtedfrom the descrambling circuit 208 to the AV decoder 209. The AV decoder209 demultiplexes multiplexed compressed audio and video data, expandsthe audio and video data, and then outputs the expanded video and audiosignals.

As described above, the preferred embodiment has the followingparticular advantageous effects.

First of all, the CPU 212 of FIG. 3, which is system control means ofthe optical disk reproducing apparatus 200 such as a DVD player or thelike, reads in the content control information 134 such as informationon the limit of the number of copies and information on downsamplingcontrol to be performed at the time of reproducing. Upon controlling theoptical disk reproducing apparatus 200, the content control informationcan be easily referred to because the non-scrambled content controlinformation is recorded.

The content control information 134, which is not scrambled from theabove-mentioned viewpoint, is recorded. When the content controlinformation 134 is tampered with, correct descramble key informationcannot be generated because of the provision of the key converter unit310. Therefore, unauthorized reproducing can be prevented.

The content data, which is easy to change in a unit of sector, is usedfor obtaining the scramble key information from the second cipher keyinformation by the use of the content control information 134. Thus,even if the content control information 134 is recorded in a unit of theabovementioned file as shown in FIG. 1 and the second cipher keyinformation is recorded in a unit of disk, the intensity of theprotection of contents by scrambling can be improved because thescramble key information changes sector by sector.

Second Preferred Embodiment

FIG. 5 is a hierarchy diagram showing a data structure of the opticaldisk 201 according to a second preferred embodiment of the presentinvention, and FIG. 6 is block diagram showing an internal configurationof a descrambling circuit 208 a for use in the second preferredembodiment. In FIGS. 5 and 6, the same components as those shown inFIGS. 1 and 4 are indicated by the same reference numerals. The datastructure of the optical disk 201 according to the second preferredembodiment and the configuration and operation of the descramblingcircuit 208 a, more particularly, a difference between the first andsecond preferred embodiments will be described in detail below.

In the first preferred embodiment, the first cipher key information isstored as the scramble information file 120 in the data recording area101, as shown in FIG. 1. In the second preferred embodiment, the firstcipher key information is stored in a scramble information sector 112 inthe control data area 110 in the lead-in area 100, as shown in FIG. 5.In the first preferred embodiment, the second cipher key information isstored in the sector 150 for storing second cipher key informationstored in the control data area 110 of the lead-in area 100, as shown inFIG. 1. In the second preferred embodiment, the second cipher keyinformation is stored together with the address information and thescramble flag in the sector header area 131 of the scrambled sector 152of the scrambled file 130 in the data recording area 101, as shown inFIG. 5.

The optical disk reproducing apparatus 200 for reproducing informationrecorded in the optical disk 201 configured as described above will bedescribed with reference to FIG. 6. The second preferred embodiment ischaracterized in that the descrambling circuit 208 shown in FIG. 4 isreplaced with the descrambling circuit 208 a shown in FIG. 6.Specifically, the descrambling circuit 208 a shown in FIG. 6 differsfrom the descrambling circuit 208 shown in FIG. 4 in the followingrespects.

(a) The first signal selector 301 is replaced with a first signalselector 301 a. The second signal selector 303 is replaced with a secondsignal selector 303 a.

(b) In the descrambling circuit 208 shown in FIG. 4, the first cipherkey information is selected by the first and second signal selectors 301and 303, and then is outputted to the first key information decoder 304.However, in the descrambling circuit 208 a shown in FIG. 6, the firstcipher key information is selected by the first signal selector 301 a,and then is outputted to the first key information decoder 304.

(c) In the descrambling circuit 208 shown in FIG. 4, the second cipherkey information is selected by the first signal selector 301, and thenis outputted to the second key information decoder 305. However, in thedescrambling circuit 208 a shown in FIG. 6, the second cipher keyinformation is selected by the first and second signal selectors 301 aand 303 a, and then is outputted to the second key information decoder305.

In other words, the descrambling circuit 208 a shown in FIG. 6 decodesthe first cipher key information which is recorded in the scrambleinformation sector 112 of the lead-in area 100 and inputted from theoptical disk controller 206. Moreover, the descrambling circuit 208 adecodes the second cipher key information and descrambles the main datain order to process the sector data having the data structure indicatedby reference numeral 110C in FIG. 5.

Next, an operation of the descrambling circuit 208 a, more particularly,a difference between the descrambling circuit 208 a and the descramblingcircuit 208 according to the first preferred embodiment shown in FIG. 4will be described in detail with reference to FIG. 6.

When input data is the first cipher key information recorded in thescramble information sector 112 in the control data area 110 in thelead-in area 100, the first signal selector 301 a outputs the inputfirst cipher key information to the first key information decoder 304.On the other hand, when input data is the sector data recorded in thedata recording area 101, the first signal selector 301 a outputs theinput sector data to the second signal selector 303 a. Subsequently, thesector data outputted from the first signal selector 301 a is inputtedto the second signal selector 303 a. The second signal selector 303 aselects a circuit to which the sector data is to be outputted, inaccordance with the location of the sector data in the sector, i.e., thecount of the number of sector data. As shown in FIG. 1, the type of thesector data recorded in the data recording area 101 is determined inaccordance with the location of the sector data in the sector. Thus, inaccordance with the count of the number of sector data, as shown in FIG.6, the second signal selector 303 a performs the operation of:

(a) outputting the input second cipher key information to the second keyinformation decoder 305 when the input sector data is the second cipherkey information;

(b) outputting the input copy control data to the first key informationconverter 311 of the key converter unit 310 when the input sector datais the copy control data;

(c) outputting the input reference data to the second key informationconverter 312 of the key converter unit 310 when the input sector datais the reference data;

(d) outputting the input scramble flag to the third signal selector 307when the input sector data is the scramble flag; or

(e) outputting the input main data to the data descrambler 306 and thethird signal selector 307 when the input sector data is the main data.

An operation of the optical disk reproducing apparatus 200 according tothe preferred embodiment configured as described above will be describedwith reference to FIGS. 3 and 6. In FIG. 3, the descrambling circuit 208is replaced by the descrambling circuit 208 a.

When the optical disk 201 is inserted into the optical disk reproducingapparatus 200 at power-on, or when the optical disk 201 is newlyinserted into the optical disk reproducing apparatus 200, the opticaldisk reproducing apparatus 200 executes decoding of the first cipher keyinformation recorded in the scramble information sector 112 in thecontrol data area 110 in the lead-in area 100. The CPU 212 controls theservo controller 211 so that information data in the scrambleinformation sector 112 in the control data area 110 in the lead-in area100 may be read out from the optical disk 201 by using the optical head203. An electric signal of the readout information data is amplified,demodulated and subjected to error correction by the head amplifier 204,the analog processor 205 and the optical disk controller 206,respectively. Then, the information data subjected to error correctionis stored in the error correction memory 207. Moreover, the CPU 212 setsthe mode of decoding the first cipher key information as the decodingmode setting information for the descrambling circuit 208 a. The CPU 212controls the optical disk controller 206 and the descrambling circuit208 a so that the data on the first cipher key information subjected toerror correction in the scramble information sector 112 may betransferred from the optical disk controller 206 to the descramblingcircuit 208 a.

The mode of decoding the first cipher key information is set in thedescrambling circuit 208 a. Thus, the input data on the first cipher keyinformation stored in the scramble information sector 112 is transferredto the first key information decoder 304 by the first signal selector301 a. The transferred first cipher key information is decoded into thefirst key information by the first key information decoder 304 using thefixed key information read out from the fixed key information memory302. Then, the first key information is outputted to the second keyinformation decoder 305. In the mode of decoding the first cipher keyinformation, no data is outputted from the descrambling circuit 208 a.

Next, an operation of selecting a file in accordance with operation byan apparatus user or the like, and then reproducing a video signal andan audio signal will be described.

The CPU 212 controls the servo controller 211, the optical head 203, theanalog processor 205 and the optical disk controller 206, therebyreading out desired information data from the optical disk 201, and thencausing the error correction memory 207 to store the information datasubjected to error correction. Moreover, the CPU 212 sets the mode ofdescrambling data for the descrambling circuit 208 a. The CPU 212 setsinformation data required for the AV decoder 209, and then controls theerror correction memory 207 to transfer the information data subjectedto error correction to the descrambling circuit 208 a.

In the descrambling circuit 208 a, the mode of descrambling data is setas the decoding mode setting information. Thus, the input sector data istransferred to the second signal selector 303 a by the first signalselector 301 a. The second signal selector 303 a counts the number ofinput sector data and selectively outputs the input sector data inaccordance with the count in the following manner.

(a) When the above-mentioned count indicates second cipher keyinformation 133 in the sector header area 131, the second cipher keyinformation 133 in the sector data is outputted to the second keyinformation decoder 305.

(b) When the above-mentioned count indicates the data locationcontaining the copy control information 136, the copy controlinformation 136 in the sector data is outputted to the first keyinformation converter 311.

(c) When the above-mentioned count indicates the data locationcontaining the reference data 137, the reference data 137 in the sectordata is outputted to the second key information converter 312.

(d) When the above-mentioned count indicates the data locationcontaining the main data, the main data is outputted to the datadescrambler 306 and the third signal selector 307.

The second cipher key information inputted to the second key informationdecoder 305 is decoded into the second key information by using as a keythe first key information outputted from the first key informationdecoder 304. The second key information obtained through decoding isoutputted to the first key information converter 311 of the keyconverter unit 310.

Subsequently, the second key information obtained through decoding isconverted into the second key information subjected to first keyinformation conversion by the first key information converter 311 by theuse of the copy control information 136 contained in the main data.Then, the converted second key information is outputted to the secondkey information converter 312. The second key information subjected tofirst key information conversion is converted into the converted secondkey information by the second key information converter 312 by the useof the reference data contained in the main data. The converted secondkey information is outputted as the descramble key information to thedata descrambler 306. Then, the main data inputted to the datadescrambler 306 is descrambled by using the descramble key informationoutputted from the second key information converter 312 of the keyconverter unit 310. Then, the descrambled main data is outputted to thethird signal selector 307.

Subsequently, the third signal selector 307 selects either thenon-descrambled main data outputted from the second signal selector 303a or the descrambled main data outputted from the data descrambler 306in accordance with the scramble flag outputted from the second signalselector 303 a and the count of the number of sector data counted in thethird signal selector 307. Then, the third signal selector 307 outputsthe selected main data to the AV decoder 209. When the scramble flag isequal to “1” and the count does not indicate the storage area for thenon-scrambled data 163, i.e., when the main data is scrambled, the thirdsignal selector 307 selects the descrambled main data outputted from thedata descrambler 306, and outputs the descrambled main data to the AVdecoder 209. On the other hand, when the scramble flag is equal to “1”and the count indicates the storage area for the non-scrambled data 163,or when the scramble flag is equal to “0”, i.e., when the main data isnot scrambled, the third signal selector 307 selects the non-descrambledmain data outputted from the second signal selector 303 a, and outputsthe non-descrambled main data to the AV decoder 209.

In the preferred embodiment, the second cipher key information may bestored in one scrambled sector 152, or a plurality of data into whichthe second cipher key information is divided may be stored in thescrambled files 130 of a plurality of scrambled sectors 152.

As described above, according to the second preferred embodiment, inaddition to the advantageous effects of the first preferred embodiment,the second cipher key information can be recorded in a unit of sector orfile. Thus, the second cipher key information can be changed in a unitof sector or file. Therefore, the intensity of copyright protection byscrambling can be further improved.

Modified Preferred Embodiments

In the above-mentioned preferred embodiments, the description is givenwith regard to the optical disk, the method of reproducing informationrecorded in the optical disk and the apparatus for reproducinginformation recorded in the optical disk. However, the present inventionis not limited to this. The present invention can be applied to aninformation recording medium including a magnetic recording medium suchas a floppy disk and a memory such as a flash memory, an EPROM or anEEPROM, a method of reproducing information recorded in the informationrecording medium and an apparatus for reproducing information recordedin the information recording medium.

In the above-described preferred embodiments, a scrambled and recordedpart of the content information 138 is obtained through scrambling usingthe scramble key information, which is obtained by converting the firstand second cipher key information by the use of a non-scrambled part ofthe content information 138. However, the present invention is notlimited to this. A scrambled and recorded part of the contentinformation 138 may be obtained through scrambling using the scramblekey information, which is obtained by converting at least one of thefirst and second cipher key information by the use of a non-scrambledpart of the content information 138.

In the above-described preferred embodiments, the apparatus comprisesthe first and second key information decoders 304 and 305. However, thepresent invention is not limited to this. The apparatus may comprise atleast one of the first and second key information decoders 304 and 305.When the apparatus comprises only the first key information decoder 304,the first key information obtained through decoding by the first keyinformation decoder 304 is outputted to the key converter unit 310. Whenthe apparatus comprises only the second key information decoder 305, thesecond key information decoder 305 decodes the second cipher keyinformation into the second key information by using the fixed keyinformation read out from the fixed key information memory 302, and thenoutputs the second key information to the key converter unit 310.

In the above-described preferred embodiments, the key converter unit 310comprises the first and second key information converters 311 and 312.However, the present invention is not limited to this. The key converterunit 310 may comprise at least one of the first and second keyinformation converters 311 and 312. That is, the second key information,which is obtained through decoding by the second key information decoder305 and outputted from the second key information decoder 305, isconverted by using a part of the content information 138, e.g., at leastone of the copy control information 136 and the reference data 137, andthe converted second key information may be used as the descramble keyinformation.

In the above-described preferred embodiments, each of the keyinformation decoders 304 and 305 decodes predetermined cipher keyinformation into key information obtained through decoding, by usingpredetermined key information. However, the present invention is notlimited to this. Each of the key information decoders 304 and 305 mayconvert predetermined cipher key information into converted cipher keyinformation by utilizing a predetermined transform equation by the useof predetermined key information.

In the above-described preferred embodiments, each of the keyinformation converters 311 and 312 converts predetermined cipher keyinformation into converted cipher key information by utilizing apredetermined transform equation by the use of predeterminedinformation. However, the present invention is not limited to this. Eachof the key information converters 311 and 312 may decode predeterminedcipher key information into key information obtained through decoding,by using predetermined key information.

As described in detail above, according to the present invention, thereis provided an information recording medium for recording at leastcopyrighted content information and cipher key information, and in theabove-mentioned information recording medium, a part of the contentinformation is scrambled and recorded, and the scrambled and recordedpart of the content information is obtained through scrambling usingscramble key information which is obtained by converting the cipher keyinformation by the use of a non-scrambled part of the contentinformation. Therefore, the present invention has the followingparticular advantageous effects.

System control means of an information reproducing apparatus, such as aDVD player or the like, reads in a part of the content information,which is the content control information such as information on thelimit of the number of copies and information on downsampling control tobe performed at the time of reproducing. Upon controlling theinformation reproducing apparatus, the content control information canbe easily referred to because the non-scrambled content controlinformation is recorded.

Moreover, a part of the content information, such as the content controlinformation, is not scrambled and is recorded. When a part of thecontent information, such as the content control information, istampered with, correct descramble key information cannot be generated.Therefore, unauthorized reproducing can be prevented.

Furthermore, the content data, which is easy to change in a unit ofsector, is used for obtaining the scramble key information from thecipher key information by the use of a part of the content information,such as the content control information or the like. Thus, even if apart of the content information, such as the content control informationor the like, is recorded in a unit of file and the cipher keyinformation is recorded in a unit of disk, the intensity of protectionof contents by scrambling can be improved because the scramble keyinformation changes sector by sector.

Furthermore, non-scrambled data is used as the reference data togenerate the scramble key information. Thus, for example, even if thecipher key information or the copy control information is set in a unitof file, the scramble key information changes in a unit of sector.Therefore, an effect of being resistant to piracy is achieved.

Furthermore, when the cipher key information is recorded in a unit ofsector or file, the cipher key information can be changed in a unit ofsector or file. Therefore, the intensity of copyright protection byscrambling can be further improved.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

1. An information recording medium for recording scrambled data from arecording device including scrambled key information, the informationrecording medium comprising: cipher key information that is scrambledand prestored on the information recording medium; non-scrambled dataincluding copy control information that is not scrambled, from contentdata which is acquired from an entity other than the informationrecording medium; and the scrambled data obtained by scrambling thecontents data using the scrambled key information, wherein the scrambledkey information is generated in the recording device from at least thecipher key information that is read from the information recordingmedium and unscrambled by the recording device, and the copy controlinformation.
 2. A method for recording information, the methodcomprising: reading cipher key information that is scrambled andprestored on an information recording medium from the informationrecording medium to a recording device; reading copy control informationthat is not scrambled, from content data which is acquired from anentity other than the information recording medium; generating scrambledkey information using at least the cipher key information that isunscrambled by the recording device and the copy control information;scrambling the content data using the scrambled key information toobtain scrambled content data; and recording the scrambled content dataand the unscrambled copy control information onto the informationrecording medium.
 3. A method for reproducing information, the methodcomprising: reading from an information recording medium copy controlinformation that is not scrambled, scrambled content data, and cipherkey information that is scrambled and prestored on the informationrecording medium, a recording device having read and descrambled thecipher key information from the information recording medium to createthe scrambled content data; generating descrambled key information usingat least the cipher key information that is unscrambled and the copycontrol information; and descrambling the scrambled content data usingthe descrambled key information to obtain content data, wherein the copycontrol information is stored onto the information recording medium fromthe content data which is acquired from an entity other than theinformation recording medium.